Se non sbaglio, il treno arriva alle otto.

Literally, se non sbaglio means if I’m not mistaken or if I’m not wrong.

• se = if
• non = not
• sbaglio = I make a mistake / I’m mistaken

In natural English, it is often translated as if I’m not mistaken, if I remember correctly, or unless I’m mistaken.

Because Italian usually expresses this idea with the verb sbagliare (to make a mistake / to be wrong) in an active form:

• sbaglio = I am wrong / I’m making a mistake

Italian does not normally say sono sbagliato for this meaning.
Sono sbagliato would sound like I am wrong/faulty in the sense of I am defective or there is something wrong with me, which is a different idea.

So for if I’m not mistaken, Italian naturally uses:

• se non sbaglio

Italian often leaves out subject pronouns when they are already clear from the verb ending.

• sbaglio already means I make a mistake / I am wrong
• so io is unnecessary

You could say Se io non sbaglio, but it usually sounds more emphatic than needed. In normal speech, Se non sbaglio is the natural choice.

Italian, like English, often uses the present tense for scheduled future events.

So:

• il treno arriva alle otto = the train arrives at eight / is arriving at eight

This is especially common for:

• train times
• flights
• timetables
• appointments
• fixed plans

English does something similar:

• The train arrives at 8.
• My class starts at 9.

So the Italian present tense here is completely normal.

Because alle is a contraction of a + le.

For telling time, Italian normally uses:

• all’una = at one
• alle due = at two
• alle otto = at eight

So:

• a + le otto → alle otto

This is the standard way to say at eight o’clock.

In Italian, articles are used more often than in English.
So where English might sometimes say train, Italian usually says the train or uses an article.

• il treno arriva alle otto = the train arrives at eight

Without the article, treno arriva would sound incomplete or unnatural in standard Italian.

The comma separates the introductory phrase from the main statement.

• Se non sbaglio, il treno arriva alle otto.

Here, Se non sbaglio works like a parenthetical expression:
If I’m not mistaken, ...

In writing, the comma helps show that this is an introductory comment rather than part of the main clause. In speech, there is often a small pause there too.

Grammatically, yes, it begins like a conditional structure because se means if. But in practice, se non sbaglio is often used as a fixed expression meaning something like:

• if I’m not mistaken
• as far as I remember
• I think, but I could be wrong

So learners often hear it almost as a set phrase rather than a literal condition.

Yes. That is also possible.

• Se non sbaglio, il treno arriva alle otto.
• Il treno arriva alle otto, se non sbaglio.

The meaning is basically the same, but the emphasis changes slightly.

• Putting Se non sbaglio first makes the uncertainty clear right away.
• Putting it at the end makes the statement come first, then adds a softening comment.

Both are natural.

Normally, alle otto means at eight o’clock, so it points to a fairly specific time.

If you want to be less exact, Italian often uses expressions like:

• verso le otto = around eight
• intorno alle otto = around eight
• circa alle otto = at about eight

So alle otto on its own is usually understood as 8:00.

Yes. In many contexts, the Italian present tense can correspond to different English present forms depending on the situation.

• il treno arriva alle otto can be translated as:
  • the train arrives at eight
  • the train is arriving at eight

For timetables and scheduled events, English often prefers arrives, but both can work depending on context and style.

It is neutral and very natural. It works well in both everyday conversation and normal written Italian.

• Se non sbaglio is polite and common
• il treno arriva alle otto is straightforward standard Italian

So the whole sentence sounds completely normal in most situations.